Imperialism - The advent of informal empire

After 1900 the American public lost interest in its new colonies, but the
United States continued to expand its power in essentially imperialist
ways. This was true principally in the Caribbean region, where the
creation of formal and informal protectorates characterized American
foreign policy in the period after the Spanish-American War. The war had
spurred interest in the building of an isthmian canal, which was to be
built as a national project; and following Panama's secession from
Colombia in 1903, the project became a reality. The great strategic
importance of the Panama Canal, thereafter joined with the considerable
American stake in Cuba and its direct sovereignty over Puerto Rico, drew
the nation further into Caribbean affairs.

Still fearful of European intervention and solicitous of the growing
American economic interest in the area, policymakers in Washington viewed
the chronic political instability of the Caribbean and Central American
nations as an invitation to foreign penetration and an obstacle to local
development. The Roosevelt Corollary to the Monroe Doctrine, enunciated by
President Theodore Roosevelt in 1904, claimed for the United States an
"international police power," which entailed a general right
to intervene and keep order in the Western Hemisphere. Not only Roosevelt
but his successors, William Howard Taft and Woodrow Wilson, steadily
expanded American hegemony in the Caribbean. By World War I, Cuba, Panama,
the Dominican Republic, Haiti, and Nicaragua were in some kind of
protectorate status, while Puerto Rico remained an outright colony. Actual
military interventions occurred in Cuba (1906–1909), Haiti
(1915–1934), the Dominican Republic (1916–1924), Nicaragua
(1912, 1927–1933), and Panama (intermittently and on a lesser
scale).

Besides the use of special treaty relationships and military force, the
United States attempted to maintain a "monopoly of lending,"
under which Caribbean governments would borrow money only in the United
States; it also established customs receiverships in several countries,
which effectively placed their government revenues under control of the
United States. Meanwhile, private enterprise had permeated the region with
American investment and business activity, while the one-crop economies of
the Caribbean nations made them heavily dependent upon the American
market. Thus, the nominally sovereign states of the Caribbean area were
subject to American controls, both formal and informal, which made their
real status essentially colonial.

After 1898, the United States was also active in the Far East, but its
impact was weaker there than in the Caribbean. Faced with a huge and
populous China, and competing with most of the other major world powers,
American policymakers could not aspire to regional dominance or military
solutions. The "dollar diplomacy" of the William Howard Taft
administration (1909–1913) attempted to foster American investment
in China and to create international financial arrangements, which would
impose a Caribbean-style "monopoly of lending" upon the
government of China. This attempt to mobilize American economic strength
as a diplomatic tool accomplished little in the Far East, however, on
account of both the difficulties of the situation itself and the limited
interest of the nation's business and financial leaders. The
earlier Open Door policy of 1899–1900, therefore, remained the
principal basis of policy. It represented little more than an attempt to
obtain a general agreement to preserve the existing treaty system of
shared control in China, and thus equality of economic opportunity in
China for the United States. The policy was not very effective, and the
Chinese market never came near to meeting the inflated expectations of the
West. In general, the limited objectives and relative ineffectiveness of
American activities in the Far East fell well short of real imperialism in
this period, although the United States was long a party to the treaty
system by which the Western powers jointly had imposed a limited
protectorate upon China.